Hi Tex,
Thank you for the nice video and yes there are vibrations in your video. while I was starting the engine last time there was a terrible bout of shaking that actually made me do a preflight again, then there are the deep indentations marks on the air filters in both sides against the actuator of the flaps. I have to lower the flaps before I start to mitigate it, these vibrations of the engine with changes of power settings should be absorbed normally by the airframe but I am not so sure this banging on the flaps would cause even failure of the bolts that attach the wing. I have to admit my experience with full scale airplanes is very limited but, with my extensive experience with RC models I have run across episodes in which a loose or vibrating engine or a loose connection of the tail plane caused a flutter on flight and it is so crazy it looks like an explosion with sudden destruction of the model. I love how this airplane flys and I would like to fly it without the fear of the thing coming apart without my input. I'll check for pieces of the video that shows this I have describe. I will check again the bolts that hold the engine and try to make a plan to see what I could do to stop the banging from happening in the first place. I have other videos in which the shaking in flight make you think it is a helicopter and not a sweet Drifter. thank you again and I hope you are completely right about it.